Mechanical valve tappet



United The present invention is directed to mechanical valve 'tappe'tsand is more particularly concerned with an automatieally adjustablemechanical valve tappet which is maintained in proper relation as to itscontact with the lower end of a valve stem of an internal combustionengine, or of a push rod for overhead valves, there being an eliminationof t-appet noises, such as clickings and the like, and a perfectmaintenance of the contact and with no space between the contact pointsof the tappet and valve stem or push rod, which is known as the flash,as applied to clearance between valvesterns or push rods and the contactpoints of the valves therefor, and which lash or clearance is providedby means of a shim of desired thickness between the valve tappet andavalve stem orpush rod in the adjustment of usual mechanical valvetappets.

With my invention, a novel and very elf ectivetappet structure isprovided, automatically self-adjustable and which is usable both withthe cams of cam shafts designed for the usual mechanical tappetoperation, or for the earns of cam shafts designed for hydraulic tappetswhich are automatically adjustable, between which and valve stems orpush rods no clearance or lash is present.

It is the primary object and purpose of my invention toprovide a novel,exceptionally practical and elfective v'alve tappet, usable under allconditions of internal corn bus't ion engine design, either with enginesdesigned for mechanical tapp'ets or hydraulic tappets, and which may beinstalled in new engines or used for replacement of ta'ppets in enginesin service. An understanding of the invention may be had from thefollowing desoription, taken in connection with the accompanyingdrawings, in whioh:

Fig. l is a vertical sectionsubstantially on the plane of line 11 ofFig. 3, through a tappet made in accordance with my invention, and shownin association with an operating cam therefor and an engine valve whichis openedor closed by the movements of the tappet, the parts of thetappet being shown in one position.

Fig. 2 is a fragmentary vertical section of the lower part of thetappet, with the parts thereof in another posit-ion which they takeduring engine operation,

Fig. 3 is a horizontal section and plan view, the sec- 'tion beingsubstantially on the plane of line 3--3 of Fig. 1, and

Fig. 4 a fragmentary section through the upper portion of the tappet onsubstantially the same plane as Fig. 1, the tappets in Figs. 1 and 4respectively slightly difiering in structure for use, one in conjunctionwith intake valves of internal combustion engines, and the other withthe exhaust valves thereof. y

Like reference characters refer to like parts in the diher'ent figuresof the drawing.

The tappet includes in its structure a tappet bodywhich has a closedhorizontal lower end 1 andv cylindrical walls 2 i eg'ra'l therewith, thebody being open atits upper end, and having an on drain ge ape-hingthrough the wan 2 near the lower end 1. With my invention the lowerStates. Paten (3 r 2,751,896 Ice Patented June 26, 1956 side of thelower closed end 1 which bears against the actuating cam for the tappetis in a plane inclined slightly to the horizontal. That is, the lowerside 1a, at one side of the tappet body is offset from horizontal, indicated in dotted lines, a distance of a few thousandths of an inch whichin practice may be between the limits of .005 to .015 inch .per linealinch of the diameter of the tappet body. This is to prevent axialturning of the tappet body which must be avoided in connection with thehereafter described movable weight, and to give a positive uniformstress between the cam and such body.

At the open upper end portion of the walls 2 of the body the interioropening is increased in diameter a small amount, providing an annularhorizontal shoulder below the upper end of the walls 2 against which aring 3 of metal is placed. An interiorly threaded sleeve 4 is formed atits upper endwith an integral outwardly extending annular flange 5, theexterior diameter of which is slightly less than the interior diameterof the enlarged upper portion of the opening into the body. Flange 5 islocated over the ring 3 and the sleeve extends downwardly through thecentral opening of the ring.

A specially constructed screw is threaded through the sleeve 4. Itincludes a head'6 at its upper end, from which an exteriorly threadedsection 7 extends downwardly through the sleeve 4, and having itsuppermost threads below the uppermost threads of the sleeve to avoidvanish binding or wedging, Around the screw shank an annular groove '8is cut at the lower-rend of the threaded section 7, below which is ashorter threaded section 9, having a limited number of screw threadsthereon. The shank of die screw is extended below the threaded section 9in a plain cylindrical terminal section 10 from whieh a pin 1i elitendsradially to one side. The threads are at a sufficien'tly flat pitch thatthe screw will not turn in the sleeve from downward pressure on head 6.

A weight 12 is mounted on the section ill for tree turning thereabout.The pin 11: extends through a slot 13 provided in the weight 1-2 whiohis open at its lower end at the law er end of the weight, and is of anarc fo'fifi curving upwardly and laterally as shown.

A not 14 is screwed onto the lower short threaded section 9 of thescrew, having an annularrece ssat its upper endwhich receives a splitspring ring 15 in the groove 8. Such ring "serves as a stop againstwhich the nut comes when it is applied to the threaded section 9 andscrewed thereon. The distance between the upper side of the weight 12and the lower side of the nut 9 is such that when the weight is in itsuppermost position (Fig. 2) the pin 11 is at the open lower end of theslot. The weight normally, by gravity, will drop to lower po- 'sition asin Fig. 1 with the pin at the upper closed end of the slot 13. v

The nut at opposite sides as recessed by reeesses having sides atrightan'gles to each other, preferably, as shown at 16. Suoh nut aroundits upper end portion is formed with an integral outwardly -extendingflange 17, beveled at its upper outer corners. The flange terminating atone of the recesses 16 which have been described, is cut away for adistance back from each of the sides of the other recess 16, as shown at18 in Fig, 3.

A torsion spring 19h located around the sleeve 4 which at its upperportion is of a greater diameter than at lower portion below a flange20, similar to the flange 17, and having parts thereof removed. Flange20 is'he'veled at its lower outer corners. The diameter of the nut 14between the flange 17 and a lower outwardly extending flange 14a thereonis likewise greater than of the lower portion of the sleeve 4.Therefore, the intermediate coils of the spring 19 between the nut 14and the flange 20 on the sleeve 4 is a short distaricei frorrrtheSleeve, whilethe lower end coin or the springls' Bind u on or arecinched against such'nut 14 and'the'upper coils cinched against the'upper portion of sleeve 4. The end of the lowercoil in Fig. 3. Theopposite end of the spring at its upper coil has a terminal portion 19bextending through an opening in. the flange of the interiorly threadedsleeve 4. A'split spring ring retainer 21 of spring wire is received inan annular groove at the upper end portion of the walls 2 of the tappetbody and at the inner side thereof, against which the flange 5 of thesleeve 4, at its upper side, engages. Flanges 17 and prevent the lowerand upper end coils from movement in a vertical direction.

When the tappets are to be used as replacement tappet in enginesoriginally equipped with the usual mechanical tappets, a dished washer22, as shown in Fig. 1, or two of them reversed with respect to eachother as shown in Fig. 4, are placed between the ring 3 and the flange5, of the sleeve 4. Such washer or washers in strength are less than thevalve spring with which associated, so that the dished washer or washerscompletely collapse at a load less than the pre-load of the valvespring. The washers in the trade are commonly known as Bellvillewashers. The gap between a ring 3 and the flange 5 will vary indiflerent engines, such gap being the clearance or so-called lash"selected by the designing engineer for the particular engine which hedesigns. The Bellville washers are used only in tappets which are toreplace or take the place of regular mechanical tappets. When the'tappetof my invention replaces automatic tappets of either hydraulic or otherforms, and in which the cam are of different design, the washers 22 arenot used as they are not needed, no lash or clearance being provided inengines having such type of tappets and actuating cams therefor.

The double washers 22 as shown in Fig. 4 are used with tappets which areassociated with exhaust valves, and the single washer 22 used withtappets to lift inlet valves of internal combustion engines.

The valve body 2 and the parts associated therewith are raised andlowered by the rotation of a cam 23 in the usual manner. The stem 24 ofan engine valve is engaged at its lower end by the upper side of thehead 6 of the described screw, the usual heavy spring 26 beingassociated with the valve and which when free to do so will close thevalve against its seat to make a tight closing engagement therewith.

The flanges 17 and 20 cut away as indicated at 18 on the flange 17, andsimilarly on the flange 20, facilitate the assembly of the spring 19with the sleeve 4 and nut 14, as the ends of the end coils of thesprings may be readily introduced to pass under flange 17 and overflange 20 and be turned until a sufiicient number of the end coils arearound such nut and the upper portion of the sleeve 4 and connecttherewith with a tight binding engagement.

The tension of the spring 19 is regulated through a relative turningmovement of the nut 14 as in Fig. 3 in a counterclockwise direction soas to move it with relation to the relatively fixed spring 19 and itsend 19a to wind the spring torsionally, the recesses at 16 and theshoulders behind which the end 19a of the spring engage actingsubstantially as a ratchet. When the spring is wound to a desiredtension, the tendency of the nut to turn in a clockwise direction willbring a shoulder at a recess 16 against the end 19a of the spring. Thespring is assembled under a pre-load'of suflicient amount to cause anupward push of the screw with a force of from 3 to 12 pounds inpractice.

In the operation, with the tappet in its lowermost po- 'sition as inFig. 1, and with the circular or base circle portion of cam 23 hearingagainst the side 1a of the body, the weight 12 is at its lower positionhanging upon and being supported by the pin 11. On rotation of the camto lift the tappet such weight remains in lower position until theuppermost position of the tappet is reached. At the peak of its riseagainst the cam the tappet body stops and the weight 12, due to themomentum of its upward movement, moves upwardly on the section 10 of thescrew and strikes against the lower side of the nut 14, at which timethe weight is moving solely in a vertical direction, as the pin 11 (Fig.2) is in the substantially vertical lower end portion of the slot 13.The weight remains in such position as the tappet body and other partsassociated therewith move downwardly with accelerated speed, until thetappet has reached its lowermost position and is stopped against furtherdownward movement, resting upon the circular or base circle portion ofthe cam. The weight thereupon moves downwardly and is spun about thevertical axis of the screw, striking the pin 11 at the upper closed endof the slot 13 with an impact force in a horizontal direction, whichturns the screw at its threaded section 7 in the sleeve 4 in a downwarddirection, making a clearance between the valve stem 24 and the head 6of the screw. This insures that the valve 25 will reach and properlyengage its seat so as to close the port of the engine at which the valveis located.

While the lower end of thebody 1 is upon the circular or base circleportion of the cam 23, such clearance is automatically taken up by thetorsion spring 19 which will turn the nut 4 and the screw in theopposite direction until the head 6 comes against the lower end of thevalve stem 24. The difference between the amount that the screw is thuswound back by the spring 19, and that it was operated in the oppositedirection by the impact of the weight 12 on the pin 11 is the amount ofvalve growth on the preceding cycle of the engine.

It is of course apparent that when the clearance between the valve stem24 and the head 6 of the screw occurs through the impact of the weight12 against the pin 11, the washer or washers 22 in those installationswhere they are used will tend to resume their normal position, and thereturn of the screw head 6 against the head of the valve stem 24 will bewith the ring 3 and flange 5 separated as shown in Fig. 1, therebyproviding the constant clearance required for running on the cams of acam shaft designed to accommodate standard lash type lifters. Suchwasher or washers are completely collapsed when, upon the upwardmovement or'lift of the tappet, the force of the valve spring 26 comesinto action holding the valve closed until such collapse has occurredafter which the valve is lifted. To insure the cinching eflect of theend coils of the spring 19 upon the nut 14 and upon the upper portion ofthe sleeve 4 the outer sides of the nut, where such spring is located,and of the sleeve, are preferably disposed at a slight angle to thevertical diverging downwardly and outwardly on the nut and upwardly andoutwardly on the sleeve,-

respectively.

The slot 13 in the weight 12 has a constant radius, and such slot islocated in such a manner as to allow the upper closed end of the slot tostrike the pin a blow in a horizontal direction to wind the torsionspring 19. The lower end of the slot is located so that in associationwith the pin 11 the weight is impelled to move vertically before theupper surface of the weight 12 and the lower surface of the nut 14strike one another. The slot 13 is at one side only of the weight andmust be angularly placedwith respect to the pin 11 to allow linecontactbetween such pin and the upper closed end of the slot." A

close or flush contact between the pin and the weight should be avoidedin order to eliminate a cushion action under such circumstances, whenboth the weight and the pin are covered with lubricating oil.

With the tappet structure described, changes in longi-, tudinaldimensions of the valve stem or a push rod in the case of overheadvalves caused by changing temperatures are immediately compensated for,there being a maintenance of contact of the head of the screw with thelower end of the valve stem or of a push rod there against at all timeswhen the tappet is doing its work of lifting the valve. The onlyclearance which takes place between the screw head and the valve stem orpush rod is for substantially an instant of time as the tappet reachesits lower-most position to insure positive and complete setting of thevalve against its seat, with substantially instantaneous closing of suchclearance through the action of the spring 19. Such clearance and itsclosure occurs at each cycle of engine operation and insures that underall temperature and other conditions of the engine the tappet, whenlifting the valve and for a short period of time before the liftingoccurs, will be in contact with the valve stem or push rod, and therewill be no noises or impingement of the head of the screw against valvestem or push rod during the time that the longitudinal expansion ofvalve stem or push rod occurs after starting a cold engine and until itis fully warmed up; or at other times when tappets are faultilyadjusted. There is also assurance that valves will always be closed whenthey should be. is far simpler in structure and operation than ahydraulic tappet, less liable to get out of order and need repair orreplacement, more economical to produce and serves fully every purpose,function and effect, insofar as elimination of noise and assuring propervalve operation are concerned, as do hydraulic tappets. Also hydraulictappets are prone to leak down oil therein when stopped at any portionof the associated cam rise, which is eliminated with the present tappet,which does not have oil leakage.

The invention is defined in the appended claims and is to be consideredcomprehensive of all forms of structure coming within their scope.

I claim:

1. An insert mechanism adapted to be entered at the upper end of andinto a vertically positioned tappet hollow body having a closed lowerend comprising, a vertically positioned screw having a head at its upperend, an upper longer threaded section and a shorter lower threadedsection spaced from the upper threated section, said screw having agroove therearound between said threated sections and said screw, belowthe lower threaded section having a downwardly extending cylindricalplain section, a pin extending radially from said last mentioned plainsection, a ring member in said groove of the screw, a nut threaded onthe lower threaded section adapted to The tappet is noiseless,

come against said ring at its upper side, a second longer nut threadedon the upper threaded section and spaced at its lower end from the firstmentioned nut, said second nut having an outwardly extending annularportion, abutment means supported by said hollow body engageable by saidannular portion to limit the movement of said second nut inwardly of thebody, a coiled spring attached at its upper end to the upper nut and atits lower end to the lower nut, and a weight through which the lowerpain section of the screw freely passes, said weight having a curvedslot therein, from its lower edge extending upwardly and laterally, saidslot being closed at its upper end, into which slot said radiallypositioned pin extends.

2. A structure as defined in claim 1, wherein said annular portioncomprises an annular flange at the upper end portion or" said upper nut,having an exterior diameter adapted to closely approach the interiorcylindrical sur face of a tappet body into which said mechanism isinserted, and said abutment means comprises an annular ring having anexterior diameter substantially the same as the exterior diameter ofsaid flange located around said upper screw below said flange, and adished ring washer between said flange and ring adapted to yield andflatten upon pressure thereagainst, said ring being adapted to havesupport upon a tappet body below the upper end of such body.

3. A structure having the elements defined in claim 1, said coiledspring at its upper portion having a gripping connection with the uppernut and at its lower end portion having a gripping connection with thelower nut, the lower end portion of said upper nut, below where theupper end of the spring has gripping connection therewith, being ofreduced diameter.

References Cited in the file of this patent UNITED STATES PATENTS1,798,508 Tucker Mar. 31, 1931 2,050,766 Russell Aug. 11, 1936 2,066,976Holmes Jan. 5, 1937 2,406,817 Engemann Sept. 3, 1946 2,433,089 BurkhardtDec. 23, 1947 2,468,332 Johnson Apr. 26, 1949 2,630,792 Engemann Mar.10, 1953 2,633,112 Engemann Mar. 31, 1953

